Borrowed Funds (Narrative) (Details) $ in Millions	Mar. 31, 2025 USD ($)
Parent Company | Senior debt
Debt Instrument [Line Items]
Basis adjustments - Fair value accounting hedges	$ (281)
Parent Company | Subordinated debt
Debt Instrument [Line Items]
Basis adjustments - Fair value accounting hedges	(52)
Subsidiaries | Senior debt
Debt Instrument [Line Items]
Basis adjustments - Fair value accounting hedges	(61)
Subsidiaries | Subordinated debt
Debt Instrument [Line Items]
Basis adjustments - Fair value accounting hedges	$ (105)